HOUSTON (AP) — During an emotional day of testimony, Russell Yates tearfully described his wife as a loving mother who was a victim of mental problems that worsened in the months before she drowned their five children in a bathtub.

Yates smiled at his wife as he entered the courtroom to testify on her behalf Wednesday. Andrea Yates, 37, has confessed to drowning the couple's five children but has pleaded innocent by reason of insanity. She could face the death penalty if convicted.

The couple mouthed words of encouragement to each other on Wednesday as defense attorneys played home movies of their children watching butterflies and greeting their mother after the birth of her fifth child. The tape was an attempt by defense attorney to depict a nurturing mother who they say became so severely mentally ill that she killed her children.

"She's wonderful," Russell Yates testified through teary eyes. "She was so involved with the children. She loved them and read to them."

Prosecutors say Andrea Yates suffered from a mental illness but knew the difference between right and wrong at the time of the drownings. To prove insanity, the defense must show the Houston woman didn't know the difference.

The husband, who sometimes rocked nervously on the witness stand, recounted his wife's mental decline in the months before the killings, but insisted she posed no threat.

"We didn't see her as a danger," Russell Yates said.

He said his wife attempted suicide twice in 1999, following the birth of Luke, their fourth child.

Russell Yates contradicted the earlier testimony of a psychiatrist who treated his wife, saying Dr. Eileen Starbranch discouraged, not forbid, the couple from having more children. He also said Starbranch took Andrea Yates off anti-psychotic medication, a contention the doctor denied in testimony earlier Wednesday.

Andrea Yates became pregnant with Mary, their fifth child, after she got back to her "old self," following the family's move into their southeast Houston home, Russell Yates said. After Mary's birth in November 2000, the depression returned, he said.

The event that again triggered Andrea Yates' disturbing symptoms, however, was the death of her father last March, he said.

"That was very traumatic for her," Russell Yates said. "She became more withdrawn and day-by-day there were more symptoms."

He testified that he took his wife to Devereux psychiatric hospital, which was closer to their home than Starbranch and the private facility Memorial Spring Shadows Glen. She was placed under the care of psychiatrist Dr. Mohammed Saeed.

Andrea Yates was discharged after about two weeks, he said, but her condition continued to worsen and he had her readmitted to Devereux about six weeks later.

Yates' attorney, George Parnham asked Russell Yates why he sent his wife back to Saeed's care after what appeared to be unsuccessful treatment the first time.

"I guess, at the time, I saw all psychiatrists as the same," Yates said. "They all have diplomas on the wall. It was my mistake."

Yates told jurors that his wife spent 10 days at Devereux before being discharged, with many of the same symptoms still apparent. When he arrived to take her home, Andrea Yates was holding her bag by the entrance and was flanked by a couple of nurses, he said.

"They knew she was sick," he said. "She was the sickest patient in that facility."

With his wife's condition still concerning him about three weeks later, Russell Yates said he asked that Saeed keep his wife on the anti-psychotic drug Haldol. Saeed recommended that she be weaned from the drug on June 4, he said.

Russell Yates said he and his wife returned to see Saeed on June 18, two days before the children's drownings, but the doctor didn't place her back on the anti-psychotic drug and changed her prescription.

Shortly after the killings, Andrea Yates told police she methodically drowned children Noah, 7; John, 5; Paul, 3; Luke, 2; and 6-month-old Mary.